Vitamin A
Function
Vitamin A, also known as retinol or beta-carotene, enhances immunity especially in the skin and membranes. It also helps repair epithelial tissue of which the skin and membranes are composed. Vitamin A prevents night blindness and is important for eye health. Vitamin A is also important for the formation of bones and teeth, aids in fat storage, and protects against colds and flu, kidney, bladder, lung and mucous membrane infections. Vitamin A is an antioxidant. Beta-carotene (and other carotenoids), another powerful antioxidant, acts as a precursor to vitamin A and increases the bodies capacity for storing vitamin A since beta-carotene can be stored safely and easily in throughout the tissues of the body. In fact you can see orange shading within the skin (usually the hands first) after consuming large amounts of carotenoids (carrots, squash, etc) over a period of weeks or months. Vitamin A can be taken in supplement form.
Sources
Sources of vitamin A include plant sources such as green and yellow vegetables, green and yellow fruits, many herbs, and animal sources such as fish and fish liver oils and animal livers. Animal sources are up to six times stronger than plant sources.
Deficiency
Dry hair, skin and eyes, poor growth, night blindness, insomnia, fatigu,e and acne are all potential deficiency symptoms.